Wire guide with multiple tips

ABSTRACT

A medical wire guide may include a mandril having a distal tip, a first coil coupled with the distal tip of the mandril, and a second coil configured to releasably engage with the mandril or the first coil. The second coil comprises a distal tip and defines an inner cavity dimensioned to contain a distal tip of the first coil when the second coil is engaged with the mandril or the first coil.

The present patent document is a divisional application that claims thebenefit of priority under 35 U.S.C. § 120 of U.S. patent applicationSer. No. 13/569,758, filed Aug. 8, 2012 which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

This application relates to medical devices and, more particularly, to awire guide with a plurality of usable tips.

BACKGROUND

Wire guides are commonly used to introduce a wide variety of medicaldevices into a patient's vascular system or other bodily lumen. Forexample, wire guides may be used in angioplasty procedures, diagnosticand interventional procedures, percutaneous access procedures, orradiological and neuroradiological procedures in general. A traditionalwire guide may include an elongated core element and a flexible helicalcoil at a distal end portion of the core element. The wire guide mayalso include a handle at the proximal end of the core element to steerthe wire guide as it is being advanced through a patient's vascularsystem or other bodily lumen.

Wire guides may encounter various challenges as they are moved through apatient's vascular system or other bodily lumen. As one example, in apedal access procedure the wire guide is inserted from the foot (pedal)so that the wire guide can traverse up into the leg below the targetsite. In such a procedure, assistance may be needed to direct the distaltip of the wire guide into a branch of the limb's vascular system. Forexample, the wire guide may experience a 90 degree or greater turn fromthe main vessel into the branching targeted vessel. Therefore, aphysician may insert a snare into the patient from a second accesslocation above the target site. The physician may use the snare to grabthe wire guide at the tip and direct it into the branching vessel.Although the snare may help guide the tip of the wire guide, thiscontact between the snare and the wire guide tip may permanently damagethe tip.

A wire guide may also be damaged in other procedures. For example, thepatient's vascular system or other bodily lumen may contain occlusionsthat impede the wire guide along its path. The physician may attempt tobreak apart the occlusion by pushing the wire guide through theocclusion, but this contact between the distal tip of the wire guide andthe occlusion may damage the distal tip.

When the distal tip of the wire guide is damaged, further use of thewire guide may be difficult for the physician or dangerous to thepatient. Thus, a need exists for an improved wire guide.

BRIEF SUMMARY

In one implementation, a medical wire guide is provided that includes amandril having a distal tip, a first coil coupled with the distal tip ofthe mandril, and a second coil configured to releasably engage with themandril or the first coil. The second coil comprises a distal tip anddefines an inner cavity dimensioned to contain a distal tip of the firstcoil when the second coil is engaged with the mandril or the first coil.

In another implementation, a medical wire guide is provided thatincludes a mandril having a distal tip, a first coil coupled with thedistal tip of the mandril, and a second coil. The first coil has aninterlocking portion and a distal end portion. The distal end portion ofthe first coil tapers in from a dimension of the interlocking portion ofthe first coil. The second coil has an interlocking portion, a distalend portion, and an inner cavity between the interlocking portion andthe distal end portion. The interlocking portion of the first coil isdimensioned to releasably engage with the interlocking portion of thesecond coil. The distal end portion of the first coil is containedwithin the inner cavity of the second coil when the interlocking portionof the second coil is engaged with the interlocking portion of the firstcoil.

In yet another implementation, a medical wire guide is provided thatincludes a mandril having a body portion and a distal tip, a first coilcoupled with the distal tip of the mandril, a cannula having a proximalend and a distal end, and a second coil having a proximal end and adistal end. The proximal end of the cannula is configured to releasablyengage with the body portion of the mandril, and the first coil iscontained within the inner cavity of the second coil when the cannula isengaged with the body portion of the mandril.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the figures are not necessarily to scale. Moreover, inthe figures, like referenced numerals designate corresponding partsthroughout the different views.

FIG. 1 illustrates a mandril for a wire guide.

FIGS. 2 and 3 illustrate coils for a wire guide.

FIG. 4 illustrates a safety wire for a wire guide.

FIG. 5 illustrates the safety wire of FIG. 4 coupled with the coil ofFIG. 3.

FIGS. 6-10 illustrate a first wire guide assembly using the componentsof FIGS. 1-5.

FIGS. 11-13 illustrate a cannula for a wire guide.

FIGS. 14 and 15 illustrate coils for a wire guide.

FIGS. 16A and 16B illustrate a mandril for a wire guide.

FIGS. 17-19 illustrate a second wire guide assembly using the componentsof FIGS. 11-16.

FIGS. 20A, 20B, 21A, and 21B illustrate alternative mandrils for use inthe second wire guide assembly of FIGS. 17-19.

FIG. 22 illustrates a completed wire guide assembly that uses themandril of FIG. 21.

FIG. 23 illustrates an alternative way to connect an inner coil and anouter coil of a wire guide.

DETAILED DESCRIPTION

This detailed description describes a medical wire guide that possessesa plurality of usable tips. For example, a first one of the wire guidetips may be used and then removed, revealing a fresh tip that residesbeneath the first tip on the same end of the wire guide. A wire guidewith multiple usable tips may be especially beneficial for medicalprocedures that require different tip properties at different stages ofthe procedure or for medical procedures that commonly result in damageto the leading tip of the wire guide. For example, a wire guide withmultiple tips would allow a physician to remove a damaged wire guide tipand then continue to use the same wire guide with the newly revealedsecond tip to complete the procedure. Having multiple usable tips in awire guide could save the time and materials that would otherwise bewasted by removing the damaged wire guide and inserting a new wire guideto complete the procedure after the first wire guide was damaged. Thesesavings are especially helpful given the rise of health care costs.

The wire guide assemblies described herein are formed from a pluralityof components, including mandrils, coils, safety wires, and cannulas,which will each be described below in connection with FIGS. 1-22. Asused herein, the term “proximal” refers to a portion of the wire guide(or a portion of any device component) closer than another portion to aphysician when the wire guide is inserted into a patient, and the term“distal” refers to a portion of the wire guide (or a portion of anydevice component) closer than another portion to the end of the wireguide that is inserted into the patient's body.

FIG. 1 illustrates a mandril 10 for a wire guide. The mandril 10 of FIG.1 includes a body portion 12, a shoulder portion 14, a tapered distalportion 16, and a distal tip 18. The mandril 10 may comprise a core wireor solid shaft with a distal end and a proximal end. The distal tip 18may be disposed at the distal end of the mandril 10. A handle (notshown) may be disposed at the proximal end of the mandril 10. The handlemay be used to pull the mandril 10 in a proximal direction.Alternatively or additionally, the handle may be used to push themandril 10 in a distal direction or twist the mandril 10. Suchmanipulations may steer the wire guide along its path through thevascular system or other lumen. The handle may be formed to have a lowprofile so that a medical device (e.g., a catheter) may pass over thehandle and continue to pass over the remainder of the wire guideunimpeded.

The mandril 10 may be formed of a suitable metallic material such asmedical grade stainless steel, a stainless steel alloy, a super-elasticmaterial including a nickel-titanium alloy (e.g., Nitinol), aliner-elastic material, or combinations of these materials.Alternatively, other suitable mandril materials may be used. The mandril10 may include a radiopaque material, such as platinum or gold.Inclusion of a radiopaque material may increase the visibility of thewire guide within the body of a patient. In some implementations, aradiopaque material may be included in other portions of the wire guide,such as in the various coils, safety wires, and cannulas.

It will be appreciated that the mandril 10 may take one of manydifferent shapes. In some implementations, the mandril 10 has a circularcross-sectional shape. In other implementations, the mandril 10 has arectangular cross-sectional shape. In yet other implementations, thecross-section of the mandril 10 assumes different shapes along thelength of the mandril 10. The mandril 10 may have a cross-sectional areathat remains substantially constant along its length. Alternatively, themandril 10 may have a cross-sectional area that varies along its length.In one implementation, the mandril 10 has a cross-sectional area thatdiminishes gradually or stepwise at increasing distances from theproximal end of the wire guide such that the mandril 10 tapers to asmaller diameter toward its distal end. For example, as shown in FIG. 1,the mandril 10 may include the tapered distal portion 16 of a reduceddiameter. The tapered distal portion 16 may increase the flexibility ofthe distal end of the wire guide.

The shoulder portion 14 of the mandril 10 may be ground into thebeginning of the taper to provide a supporting surface for abutting acoil. The shoulder portion 14 may also provide a soldering surface forconnecting a coil with the mandril 10. In one implementation, theshoulder portion 14 may be larger than the diameter of the coil abuttingthe shoulder portion 14 so that the coil cannot pass over the shoulderportion 14. The distal tip 18 of the mandril 10 may include a barrel atthe end of the taper. The barrel of the distal tip 18 may providesupport and an increased surface area for binding with a coil.

FIG. 2 illustrates a coil 20 for one implementation of a wire guideassembly. The coil 20 may be a helical shaped wound coil formed bywinding a wire into a plurality of rings (e.g., wire turns). The coil 20may be wound by a coiling machine that presses the wire against a wedgeto make the wire curve into a coil shape. The coiling machine cancontrol the pitch and diameter of the coil according to the operator'spreferences. The wire used to form the coil 20 may be made from asuitable metallic material such as platinum, palladium, medical gradestainless steel, a stainless steel alloy, a super-elastic materialincluding a nickel-titanium alloy (e.g., Nitinol), a liner-elasticmaterial, or combinations of these materials. Alternatively, othersuitable coil winding materials may be used for the coil 20.

The coil 20 includes a proximal end portion 22, an interlocking portion24, and a distal end portion 26. The interlocking portion 24 may have adifferent winding pitch than the proximal end portion 22 and the distalend portion 26. For example, as shown in FIG. 2, a plurality of coilrings in the middle of the coil 20 may have a larger pitch/width thanthe coil rings of the proximal and distal ends. In one implementation,three to five coil rings in the interlocking portion 24 of the coil 20have a larger pitch/width than the majority of the coil 20. In otherimplementations, more or fewer coil rings may be included as part of theinterlocking portion 24.

In one implementation, the proximal end portion 22 may represent 40% ormore of the total length of the coil 20, the interlocking portion 24 mayrepresent 10% of the total length of the coil 20, and the distal endportion 26 may represent 40% or less of the total length of the coil 20.Alternatively, other proportions of the length of the coil may bedevoted to the respective portions.

The entire length of the proximal end portion 22 and the interlockingportion 24 of the coil 20 may have about an equal diameter (e.g., withineither a 5%, 10%, or 20% variation in diameter). Alternatively, someportions of the proximal end portion 22 or the interlocking portion 24may taper to a narrower diameter or extend to a wider diameter. Thedistal end portion 26 of the coil 20 tapers in from a dimension (e.g.,diameter) of the interlocking portion 24 such that a distal-most segment28 of the distal end portion 26 is smaller in diameter than the diameterof the interlocking portion 24 and may be smaller in diameter than othersections of the distal end portion 26.

FIG. 3 illustrates a coil 30 that is connectable with the coil 20 ofFIG. 2 in a wire guide assembly. The coil 30 may be a helical shapedwound coil formed by winding a wire into a plurality of rings (e.g.,wire turns). The wire used to form the coil 30 may be made from asuitable metallic material such as platinum, palladium, medical gradestainless steel, a stainless steel alloy, a super-elastic materialincluding a nickel-titanium alloy (e.g., Nitinol), a liner-elasticmaterial, or combinations of these materials. Alternatively, othersuitable coil winding materials may be used for the coil 30.

The coil 30 may include an interlocking portion 32 and a distal endportion 34. The interlocking portion 32 may have a different windingpitch than the distal end portion 34. For example, as shown in FIG. 3, aplurality of coil rings at the proximal end of the coil 30 may have alarger pitch/width than the coil rings of the distal end portion 34. Inone implementation, three to five coil rings at the proximal end of thecoil 30 have a larger pitch/width than the majority of the coil 30. Inother implementations, more or fewer coil rings may be included as partof the interlocking portion 32. The entire length of the coil 30 mayhave about an equal diameter (e.g., within either a 5%, 10%, or 20%variation in diameter). Alternatively, some portions of the coil 30 maytaper to a narrower diameter or extend to a wider diameter.

FIG. 4 illustrates a safety wire 40 for a wire guide. Each of the coilsused in the wire guides described herein may be connected with a safetywire 40 to prevent the coil from being stretched or completely separatedfrom the mandril at either end. FIG. 5 illustrates the safety wire 40 ofFIG. 4 coupled with the coil 30 of FIG. 3. The left side of FIG. 5 showsa cut-away side view of the coil 30 and the safety wire 40, while theright side of FIG. 5 shows an end view looking down an inner cavity 50of the coil 30. As shown in FIG. 5, the safety wire 40 may connect adistal end portion of the coil 30 to a proximal end portion of the coil30. The safety wire 40 may pass through the inner cavity 50 of the coil30. The connection between the safety wire 40 and the coil 30 may beperformed by soldered connections 52 and 54. The safety wire 40 may runat least a portion of the length of the interior cavity 50 of the coil30 to ensure longitudinal integrity of at least a portion of the coil 30and limit some movement (e.g., stretch) of the distal end of the coil 30relative to the proximal end of the coil 30. The connection of thesafety wire 40 to a coil may occur separately in the materialpreparation stage, before assembly of the final product. Alternatively,the safety wire 40 may be connected to the coil during the assembly ofthe final product.

FIGS. 6-10 illustrate a first wire guide assembly using the componentsof FIGS. 1-5. As shown in FIG. 6, a safety wire 60 may be connected tothe mandril 10. For example, soldered connections 62 and 64 may bond thesafety wire 60 to the mandril 10, such as at the barrel and taper of themandril 10. The safety wire 60 used in FIG. 6 may be similar inconstruction as the safety wire 40 described above in connection withFIGS. 4 and 5. In one implementation, the safety wire 60 is long enoughto span the length of the wider pitch portion of the coil (e.g., theinterlocking portion of the coil 20 shown in FIG. 7) that will beconnected over the safety wire 60. As shown in FIG. 7, the coil 20 isadded over the safety wire 60 and the tapered distal end portion of themandril 10 of FIG. 6. The coil 20 may be bonded with the safety wire 60and/or the mandril 10 via one or more soldered connections.

FIG. 8 illustrates a connection between the coil 30 and the coil 20. Forexample, the coil 30 is added to the assembly illustrated in FIG. 7 byslipping the coil 30 over the coil 20 and aligning the respectiveinterlocking portions (e.g., the wider pitch portions). The coil 30 istwisted relative to the coil 20 so that the interlocking portionsintertwine together and form the appearance of one solid coil. Theinterlocking portion of the coil 20 has a wider pitch than other areasof the coil 20 to define a space 80 between adjacent rings of the coil20. The space is dimensioned to fit a corresponding ring 82 of the coil30 when the interlocking portion of the coil 30 is engaged with theinterlocking portion of the coil 20.

In one implementation, the coil 20 is soldered to the mandril 10, whilethe coil 30 is free from a direct connection with the mandril 10. Forexample, the coil 30 may be coupled with the mandril 10 by an indirectconnection through a threaded engagement with the coil 20. The threadedengagement may be disconnected by twisting the coil 30 relative to thecoil 20 in the opposite direction than used to connect the coil 30 withthe coil 20.

As shown in FIG. 9, the tip of one coil may be covered by the tip ofanother coil. For example, the distal tip 28 of the coil 20 may becontained within the inner cavity 50 of the coil 30 when the coil 30 isengaged with the coil 20. Thus, at least a portion of the distal tip 28of the coil 20 resides beneath the coil 30 when the two coils areengaged. The inner coil 20 may thus be protected from at least somedamage while the outer coil 30 is connected with the inner coil 20.

Each of the distal tips of the coils may be formed to promote atraumaticvessel navigation, such as by forming a rounded distal surface. Thedistal-most portion of the distal tip 28 of the coil 20 may be welded orsoldered to form an atraumatic distal tip usable after the outer coil 30is removed from the wire guide. As shown in FIG. 10, a distal-most tip100 of the coil 30 may also be welded or soldered to form anotheratraumatic distal tip usable before the outer coil 30 is removed fromthe wire guide. Additionally, the wire guide may include a solder joint102 to connect the coil 20 with the mandril 10. FIG. 10 illustrates thewire guide in final assembled form with multiple usable distal tips onthe same end of the wire guide, one tip from the outer coil 30 and onetip from the inner coil 20.

During a medical procedure, a physician may use the distal end of thecoil 30 as the leading distal tip of the wire guide for a first stage ofthe procedure. At some point in the procedure, the physician may want toremove the coil 30 and expose the underlying coil 20 to act as theleading distal tip of the wire guide for another stage of the procedure.As one example, the physician may want to remove the coil 30 because ithas been damaged. As another example, the physician may want to removethe coil 30 because the coil 20 has certain properties, such as anincreased flexibility, that are better suited for the next stage of theprocedure.

A physician may remove the coil 30 from the wire guide by pushing thedistal end of the wire guide out of a second access location of thepatient that is different than the first access location that was usedto begin feeding the wire guide into the patient. The distal end of thewire guide may be exposed while other portions of the wire guide arestill within a vascular passage or other bodily lumen of the patient.The coil 30 may be removed by locating an area distal to the intertwinedcoils and twisting the coil 30 relative to the coil 20 to disengage thethreaded connection between the two coils. The interlocking portions maybe visually marked in some way to enhance the ability of the physicianto locate the area of connection between the coils. The threadedconnection provides a simple removal process that may not require tools.Additionally, the threaded connection is unlikely to unscrew withtorsion while in the patient. After the coil 30 has been removed toexpose the distal tip of the coil 20, then the new distal tip of thewire guide may be retracted back into the patient through the secondaccess location to continue the medical procedure with the distal tip ofthe coil 20 now serving as the distal-most portion of the wire guide.

Having two different usable distal tips available on one end of the wireguide allows customization of the two tips for different stages of theprocedure. As a first example, the first coil 20 may be formed from adifferent material than the coil 30. The different properties of thematerials may allow the coil 30 to be formed from a relatively stiffmaterial for clearing occlusions, while the coil 20 may be formed from arelatively flexible material for traversing delicate passageways afterthe occlusions have been cleared. As a second example, the distal endportion of the coil 30 may be wound with a different pitch than thedistal end portion of the coil 20. The different winding pitches mayallow one coil to be stiffer or more flexible than the other. As a thirdexample, the coil 30 may be wound from a wire with a different diameterthan a wire used for the coil 20. The different wire diameters may allowone coil to be stiffer or more flexible than the other. As a fourthexample, the diameter of the coil 20 may be smaller than the diameter ofthe coil 30. This difference in size may allow the wire guide to gainaccess to smaller passageways when led by the coil 20 after the largercoil 30 is removed from the wire guide. As a fifth example, one of thecoils may have a curved shape. For example, the outer coil 30 may beseparately curved so that the curved portion extends beyond the lengthof the inner coil 20. This difference in coil shape allows for a wireguide with both a curved distal tip option and a straight distal tipoption. Alternatively, both coils 20 and 30 may be attached togetherwhile straight and then curved together at the same time. Thisimplementation provides a wire guide with multiple curved usable tips.One or more of the coils may be curved by stretching the coil in amanner that provides space between adjacent coil rings to define thecurve radius.

Additionally, the coils may be different from each other in multipleways. For example, the distal tip of the coil 30 may be made ofstainless steel with a very tight pitch and/or larger wire to creategreat stiffness for pushing through blockages, and the distal tip of thecoil 20 that is contained beneath the coil 30 may be made of a softermaterial with a wider pitch and/or a smaller wire diameter for usefurther into the body as vessels become smaller or more fragile. Thus,the combinations of materials, coil pitches, coil diameters, and wiresizes result in a multi-purpose wire guide that may be customized to theunique set of requirements of an individual procedure.

Although the differences in properties between the coils 20 and 30 mayprovide a benefit in some procedures and implementations, in otherprocedures and implementations there may be a benefit to having multipleavailable distal tips with the same or similar properties. For example,the coil 20 may have many of the same properties as the coil 30, andthus serves as a redundant distal tip in case the coil 30 is damagedduring use. In this situation, the coil 20 is available for use as thedistal tip to continue the procedure after the damaged coil 30 has beenremoved. Having multiple redundant distal tips on the wire guide mayprovide a solution to replacing damaged wire guide tips by savingprocedural time, hospital materials, and healthcare and proceduralcosts. It saves time and reduces the possibility of contamination byproviding a ready, fresh wire guide tip without requiring the physicianto fully remove the whole damaged wire guide and insert an entirely newwire guide to complete the procedure. For example, contamination maybecome an increasing concern when the wire in use has a length longerthan 80 cm, which may require many personnel to assist in handling. Bynot requiring the complete removal of the wire guide in someimplementations to get a new usable distal tip for the wire guide, therisk of contamination, lost time, and lost costs is reduced.

FIGS. 1-10, as discussed above, illustrate a first implementation of awire guide with multiple tips on the distal end of the wire guide. FIGS.11-22 illustrate a second implementation of a wire guide with multipletips on the distal end of the wire guide. The implementation of FIGS.11-22 includes many of the same features and benefits as theimplementation of FIGS. 1-10. For example, the implementation of FIGS.11-22 allows the customization of the properties of multiple distal tips(e.g., by selection of different materials, coil pitches, coil sizes, orthe like) and allows for the removal of a damaged distal tip to exposean underlying distal tip usable to complete the procedure, as discussedabove in connection with the implementation of FIGS. 1-10. Therefore,the properties and features discussed above in connection with theimplementation of FIGS. 1-10 are equally applicable to the correspondingcomponents of the implementation of FIGS. 11-22 unless otherwise stated.

FIGS. 11-13 illustrate a cannula 110 for the second wire guideimplementation. Specifically, FIG. 11 illustrates an isometric view ofthe cannula 110, FIG. 12 illustrates a partial cross-section view of thecannula 110, and FIG. 13 illustrates an end view of the cannula 110. Thecannula 110 may be formed of a suitable metallic material such asmedical grade stainless steel, a stainless steel alloy, a super-elasticmaterial including a nickel-titanium alloy (e.g., Nitinol), aliner-elastic material, or combinations of these materials.Alternatively, other suitable mandril materials may be used. The cannula110 acts as a coil base to connect a coil with a mandril. The cannula110 includes a hollow cylindrical passageway 112. The inner surface ofthe cannula 110 (e.g., the inner surface of the hollow cylindricalpassageway 112) includes threads 120. The threads may be used to connectthe cannula 110 with corresponding threads of a mandril. Otherconnection devices, such as latches or tabs, may be used in place of thethreads to connect the cannula 110 with the mandril. In oneimplementation, the cannula 110 is the about the same diameter (e.g.,within either a 5%, 10%, or 20% variation in diameter) as the coil thatwill be connected with the cannula 110.

FIGS. 14 and 15 illustrate coils 140 and 150 for use with the secondwire guide implementation. The coils 140 and 150 may be uniform diametercoils. For example, the entire length of each of the coils 140 and 150may have about an equal diameter (e.g., within either a 5%, 10%, or 20%variation in diameter), although the uniform diameter of the coil 140may be different than the uniform diameter of the coil 150.Alternatively, some portions of the coils 140 and 150 may taper to anarrower diameter or extend to a wider diameter. In one implementation,the coil 140 is smaller than the coil 150. For example, the diameter ofthe coil 140 may be smaller than the diameter 150 so that the coil 140is able to fit within an inner cavity of the coil 150.

The coils 140 and 150 may be helical shaped wound coils formed bywinding a wire to form a plurality of rings (e.g., wire turns). Thecoils may be wound by a coiling machine that presses the wire against awedge to curve the wire into a coil shape. The coiling machine cancontrol the pitch and diameter of the coil according to the operator'spreferences. The wire used to form the coils 140 and 150 may be madefrom a suitable metallic material such as platinum, palladium, medicalgrade stainless steel, a stainless steel alloy, a super-elastic materialincluding a nickel-titanium alloy (e.g., Nitinol), a liner-elasticmaterial, or combinations of these materials. Alternatively, othersuitable coil winding materials may be used for the coils 140 and 150.

One or both of the coils 140 and 150 may include a safety wire (e.g.,similar to the safety wire 40 shown in FIGS. 4 and 5) to prevent thecoil from being stretched or completely separated from the mandril ateither end. The safety wire may connect a distal end portion of the coilto a proximal end portion of the coil within an inner cavity of thecoil. The connection between the safety wire and the coil may beperformed by soldered connections. The safety wire may run at least aportion of the length of the interior cavity of the coil to ensurelongitudinal integrity of the coil and limit some movement (e.g.,stretch) of the distal end of the coil relative to the proximal end ofthe coil. The connection of the safety wire to a coil may occurseparately in the material preparation stage, before assembly of thefinal product. Alternatively, the safety wire may be connected to thecoil during the assembly of the final product.

FIG. 16 illustrates a mandril 160 for a wire guide. FIG. 16A shows themandril 160 without a safety wire, and FIG. 16B shows a safety wire 166coupled with the mandril 160. The mandril 160 of FIG. 16 is similar tothe mandril 10 of FIG. 1 and shares many of the properties of themandril 10. Therefore, the features, characteristics, shapes,construction, and materials of the mandril 160 match the features,characteristics, shapes, construction, and materials of the mandril 10unless otherwise highlighted here. For example, the mandril 160 includesa shoulder portion, a tapered distal portion, and a distal tip that arethe same or similar to the corresponding components of the mandril 10.Additionally, as shown in FIG. 16B, the safety wire 166 may be connectedwith the mandril 160 during assembly in a similar manner as the safetywire 60 of FIG. 6. For example, the safety wire 166 serves to protectthe longitudinal integrity of a coil connected with the safety wire 166.

The mandril 160 of FIG. 16 includes a body portion 162 with a threadedportion 164. In one implementation, the threaded portion 164 comprisesexternal threads raised up from the surface of the body portion 162. Thethreaded portion 164 serves to hold a connection with the correspondingthreaded portion 120 of the cannula 110 of FIGS. 11-13 when the cannula110 is engaged with the mandril 160.

FIGS. 17-19 illustrate a second wire guide assembly using the componentsof FIGS. 11-16. In FIG. 17, the coil 150 is connected with the cannula110, such as by soldering the coil 150 to the cannula 110. The coil 150may be connected with a safety wire to preserve the longitudinalintegrity of the coil 150. In FIG. 18, multiple coils are connected withthe mandril 160. First, the coil 140 is placed over the safety wireattached to the mandril 160 of FIG. 16. The coil 140 may be connectedwith the tapered portion of the mandril 160, such as by attaching thecoil 140 with solder at the shoulder and tip of the mandril 160. FIG. 18illustrates that the assembly of the coil 150 and cannula 110 isconnected to the mandril 160, which places the coil 140 within an innercavity 180 of the coil 150. For example, the cannula 110 may be slidover the coil 140 until the threaded portion 120 of the cannula 110meets the threaded portion 164 of the mandril 160. The cannula 110 isthen twisted relative to the mandril 160 to tighten the connectionbetween the mandril 160 and the cannula 110. The cannula 110 and coil150 can similarly be removed by twisting the cannula 110 relative to themandril 160 in an opposite direction. FIG. 19 illustrates a completedwire guide using the components of FIGS. 11-16. The distal tip of thecoil 150 may include a solder ball 190 or other rounded feature to makethe tip of the coil 150 atraumatic. Additionally, the wire guide mayinclude a solder joint 192 to connect the coil 150 with the cannula 110.

FIG. 20 illustrates an alternative mandril 200 for use in the secondwire guide implementation of FIGS. 17-19. FIG. 20A shows the mandril 200without a safety wire, and FIG. 20B shows a safety wire 204 coupled withthe mandril 200. The mandril 200 includes a threaded portion 202 thatmay be ground into the mandril 200 negatively instead of as a positiveprofile, such as the positive profile of the threaded portion of themandril 160 of FIG. 17. For example, the negative profile of thethreaded portion 202 may be formed as a channel in the surface of themandril 160. The negative profile of the threaded portion 202 wouldconnect with positive protruding threads on the inside of acorresponding cannula. The negative profile on the mandril 200 may bebeneficial in some implementations because the outer surface of themandril 200 may not have protruding threads after removal of the cannulaand associated outer coil tip.

FIG. 21 illustrates another alternative mandril 210 for use in thesecond wire guide implementation of FIGS. 17-19. FIG. 21A shows themandril 210 without a safety wire, and FIG. 21B shows a safety wire 218coupled with the mandril 210. The mandril 210 includes a body portionwith a wider proximal portion 212 and a narrower distal portion 214. Themandril 210 includes a threaded portion 216 on an outer surface of thenarrower distal portion 214. FIG. 22 illustrates a completed wire guideassembly that uses the mandril 210 of FIG. 21. Using a mandril with thethreaded portion 216 on the narrower distal portion 214 may providespace for the cannula 110 to sit so that the outer surface of thecannula 110 may be substantially flush (e.g., within either a 5%, 10%,or 20% difference in diameter) with an outer surface of the widerproximal portion 212 of the mandril 210 in the completed wire guideassembly, as shown in FIG. 22. Thus, the widest diameter of thecompleted wire guide assembly of FIG. 22 may be uniform with or withoutconnection of the outer distal tip.

In some implementations, the medical wire guides described hereininclude two usable tips. Alternative implementations of the wire guidemay include more than two usable tips. As one example, one or moreadditional coils may be interconnected with the outer coil 30 of FIG. 10in a similar manner as the coil 30 is interconnected with the coil 20.For example, the coil 30 may include a second wider pitch interlockingportion for forming a threaded connection with an additional coil thatwould provide an inner cavity to contain the coil 30. As anotherexample, one or more additional coils may be interconnected with thewire guide of FIG. 10 by adding a cannula/coil assembly (as shown inFIG. 17) over the coil 30 of the wire guide in FIG. 10.

The coils of the wire guides described herein may be releasably engagedwith each other in several different ways. As one example, FIGS. 8-10illustrate one way to connect a first coil 20 and a second coil 30. Asanother example, FIG. 18 illustrates another way to connect a first coil140 and a second coil 150. Each of these implementations has beendescribed above in more detail. FIG. 23 illustrates still another way toconnect an inner coil 230 and an outer coil 232 of a wire guide so thatthe outer coil 232 defines an inner cavity dimensioned to contain adistal tip of the inner coil 230 when the outer coil 232 is engaged withthe inner coil 230. In the implementation of FIG. 23, the inner coil 230and the outer coil 232 may be pushed towards each other to clip one coiltogether with the other coil. For example, the coils may be formed witha locking mechanism to clip one coil together with the other coil.

The locking mechanism of the implementation of FIG. 23 may include oneor more rings of the coils in a row or separated at intervals. As shownin FIG. 23, a ring 234 of the inner coil 230 may have a smallerdimension (e.g., diameter) than adjacent rings of the inner coil 230.Similarly, a ring 236 of the outer coil 232 may have a smaller dimension(e.g., diameter) than adjacent rights of the outer coil 232. When thering 236 of the outer coil 232 is aligned with the ring 234 of the innercoil 230, the ring 236 may fit into a void formed from the smallerdiameter of the ring 234. In other implementations, multiple rings witha smaller dimension (e.g., diameter) may be positioned adjacent to oneanother to form a wider interlocking region between the coils.Alternatively, spaced individual rings with a smaller dimension may bepositioned in a sequence to provide multiple interlocking regions alongthe coils.

The connection between the ring 236 and the void formed from the smallerdiameter of the ring 234 provides resistance against movement of theouter coil 232 relative to the inner coil 230. However, a physician mayintentionally pull the outer coil 232 relative to the inner coil 230with sufficient force to dislodge the ring 236 from the void formed bythe smaller diameter of the ring 234 to remove the outer coil 232 andexpose the inner coil 230 for use as the distal tip of the wire guide.

The medical wire guides described herein may be dimensioned to fitwithin a vascular passage or other body lumen. The wire guide maygenerally have a length in the range of 30-600 cm. In someimplementations, the length of the wire guide may be in the range of90-300 cm. The wire guide may generally have an outer diameter in therange of 0.204-1.321 mm (0.008-0.052 inches). In some implementations,the outer diameter may be in the range of 0.254-2.286 mm (0.01-0.09inches). For example, one type of wire guide may have an outer diameterof about 0.889 mm (0.035 inches). In other implementations, wire guidesof other dimensions (e.g., longer, shorter, wider, or narrower) may alsobe used.

While various embodiments, features, and benefits of the present deviceshave been described, it will be apparent to those of ordinary skill inthe art that many more embodiments, features, and benefits are possiblewithin the scope of the disclosure. For example, other alternate devicesmay include any combinations of structure and functions described aboveor shown in the figures.

What is claimed is:
 1. A medical wire guide, comprising: a mandrilhaving a body portion and a distal tip; a first coil coupled with thedistal tip of the mandril; a cannula having a proximal end and a distalend; and a second coil coupled with the distal end of the cannula andhaving an inner cavity; where the cannula is configured to releasablyengage with the body portion of the mandril, the first coil is containedwithin the inner cavity of the second coil when the cannula is engagedwith the body portion of the mandril, and the cannula is not axiallymovable relative to the mandril when the cannula is engaged with thebody portion of the mandril.
 2. The medical wire guide of claim 1, wherethe first coil comprises a different material, wire winding pitch, orwire diameter than the second coil.
 3. The medical wire guide of claim1, where the cannula comprises an inner surface that defines a firstthreaded area, where the mandril comprises an outer surface that definesa second threaded area, and where the cannula is configured toreleasably engage with the mandril through a threaded connection betweenthe first threaded area and the second threaded area.
 4. The medicalwire guide of claim 3, where the second threaded area of the mandrilcomprises a channel formed in the outer surface of the mandril and thefirst threaded area of the cannula comprises protruding threads on theinner surface of the cannula.
 5. The medical wire guide of claim 1,where a distal-most tip of the first coil is soldered to form a firstatraumatic distal tip, and where a distal-most tip of the second coil issoldered to form a second atraumatic distal tip.
 6. The medical wireguide of claim 1, where a diameter of the cannula is about the same as adiameter of the second coil.
 7. The medical wire guide of claim 1, whereat least one of the first coil and the second coil includes a safetywire configured to connect a distal end portion of the coil to aproximal end portion of the coil.
 8. A medical wire guide, comprising: amandril having a body portion; a first coil coupled with a distal end ofthe mandril; a cannula having a proximal end and a distal end; and asecond coil coupled with the cannula and having an inner cavity; wherethe body portion of the mandril comprises a wider proximal portion and anarrower distal portion, the cannula is configured to releasably engagewith the narrower distal portion of the body portion of the mandril, thefirst coil is contained within the inner cavity of the second coil whenthe cannula is engaged with the narrower distal portion of the mandril,and the cannula is not axially movable relative to the mandril when thecannula is engaged with the narrower distal portion of the mandril. 9.The medical wire guide of claim 8, where the first coil comprises adifferent material, wire winding pitch, or wire diameter than the secondcoil.
 10. The medical wire guide of claim 8, where the cannula comprisesan inner surface that defines a first threaded area, the narrower distalportion of the body portion of the mandril comprises an outer surfacethat defines a second threaded area, and the cannula is configured toreleasably engage with the mandril through a threaded connection betweenthe first threaded area and the second threaded area.
 11. The medicalwire guide of claim 10, where the second threaded area of the mandrilcomprises a channel formed in the outer surface of the mandril and thefirst threaded area of the cannula comprises protruding threads on theinner surface of the cannula.
 12. The medical wire guide of claim 8,where a distal-most tip of the first coil forms a first atraumaticdistal tip, and a distal-most tip of the second coil forms a secondatraumatic distal tip.
 13. The medical wire guide of claim 8, where adiameter of the cannula is about the same as a diameter of the secondcoil and a diameter of the wider proximal portion of the body portion ofthe mandril.
 14. The medical wire guide of claim 8, where at least oneof the first coil and the second coil includes a safety wire configuredto connect a distal end portion of the coil to a proximal end portion ofthe coil.
 15. A medical wire guide, comprising: a mandril having a bodyportion and a distal end; a first coil coupled with the distal end ofthe mandril; a cannula having a proximal end and a distal end; and asecond coil coupled with the cannula and having an inner cavity; wherethe body portion of the mandril comprises a wider proximal portion and anarrower distal portion, the cannula is configured to releasably engagewith the narrower distal portion of the mandril, and the first coil iscontained within the inner cavity of the second coil when the cannula isengaged with the narrower distal portion of the mandril; where thecannula comprises an inner surface that defines a first threaded area,the narrower distal portion of the mandril comprises an outer surfacethat defines a second threaded area, and the cannula is configured toreleasably engage with the mandril through a threaded connection betweenthe first threaded area and the second threaded area; and where adiameter of the cannula is about the same as a diameter of the secondcoil and a diameter of the wider proximal portion of the mandril so thatan outer surface of the cannula is substantially flush with an outersurface of the wider proximal portion of the mandril.
 16. The medicalwire guide of claim 15, where the first coil comprises a differentmaterial, wire winding pitch, or wire diameter than the second coil. 17.The medical wire guide of claim 15, where the second threaded area ofthe mandril comprises a channel formed in the outer surface of themandril and the first threaded area of the cannula comprises protrudingthreads on the inner surface of the cannula.
 18. The medical wire guideof claim 15, where a safety wire is connected to the narrower distalportion of the mandril and to the first coil to protect a longitudinalintegrity of the first coil.
 19. The medical wire guide of claim 15,where a distal-most tip of the first coil forms a first atraumaticdistal tip, and a distal-most tip of the second coil forms a secondatraumatic distal tip.
 20. The medical wire guide of claim 15, where atleast one of the first coil and the second coil includes a safety wireconfigured to connect a distal end portion of the coil to a proximal endportion of the coil.